Skylights: Naturally Lit Interiors Save Energy

Skylights are one surprising design option for a commercial building that needs to save on energy. Skylights offer many benefits including savings on artificial lighting and heating. One of the largest sources of energy consumption in commercial and industrial applications is artificial lighting.

Skylights impact the building’s energy usage in three ways, two positive and one negative, though the two positive benefits more than make up for the negative one. Skylights save energy by replacing artificial lighting with adequate natural light. This is a positive effect. Another positive effect is the amount of heating energy saved as a result of passive solar gain. (This can be a complex benefit since the design of the building and other construction materials will determine how much passive solar gain there is.) Unfortunately, skylights can lead to some heat loss, though not enough to make skylights a poor decision.

More About Skylights

Current skylights consist of insulating glazing held in aluminum frames in one of many configurations such as single slope, ridge, pyramid and barrel vault. Skylights have been used for more than a century to provide daylight to interior spaces. Early skylights consisted of plate glass — and later, wire glass — in metal frames. They frequently included both an exterior skylight and a second layer on the bottom, a decorative “diffuser” or “laylight.”

Skylights Provide Energy Savings

Some might think that having a surplus of skylights allow more heat to escape than the rest of a roof thereby increasing the running costs of the building. Research from the Institute of Energy & Sustainable Development proves that assumption wrong. Instead, the Institute finds that installing the appropriate number of skylights can reduce overall energy consumption.

Well-designed buildings with abundant natural light experience passive solar gain and need less artificial light. This means that including skylights in building design can offer a dramatic reduction in a building’s total energy consumption as well as reduced CO2 emissions. The benefits of a naturally-lit interior include the reduced energy consumption and reduced emissions, money savings, and a more pleasant environment where people what to spend time.

These are the findings of the study that the National Association of Rooflight Manufacturers (NARM) commissioned from the Institute of Energy & Sustainable Development at Leicester’s De Montfort University.

Daylight has many advantages over artificial light including that it’s an entirely free and unlimited natural resource.

When assessing the overall impact of skylights and glazing on a building’s energy efficiency of a building, there are a lot of factors to consider.

Lux is the measurement of lighting level. A light level of 300 lux is adequate for activities that don’t require the perception of detail; it is suitable for circulation spaces and assembly halls. When a degree of color judgement is required as in many retail, production and office environments, a light level of 600 lux is ideal.

An increase in skylight area, at least within the range of 0 and 20 percent, results in the reduction of total CO2 emissions.

In buildings used primarily during daylight hours during colder months, skylights actually decreases the amount of energy required for heat. For a building that is occupied between 9 a.m. and 5 p.m. for 365 days with a lighting requirement of 600 lux whose roof is 20 percent skylights, there is an impressive 85 percent savings in CO2 emissions from lighting and heat loss over the same building without skylights. When a building with skylights is occupied 24 hours a day, there are no benefits from natural light or passive solar energy.

Yet even at night, skylights can provide a significant energy benefits. When a commercial space requires a lighting level of 600 lux, energy savings are proportionate to the amount of skylight area. The more skylights there are, the better the energy savings. This is especially true for buildings that have a lighting requirement of only 300 lux, which is relatively low. In these low-lit buildings, energy consumption falls even further as the skylight area increases. In buildings that require a lighting level of just 300 lux until it reaches 14 percent.

Get the Most Out of Skylights with Automated Lighting Controls

Because of cloud movement, the amount of sunlight that comes through skylights

Research shows how important appropriate lighting controls are to maximizing the energy savings benefit. Even with skylights, artificial lights are often left on even when not needed. If artificial lights are left on even when sunlight is strong enough that the artificial lighting isn’t needed, the considerable energy savings that skylights offer are lost.

Ensure savings by using simple “on/off” automated lighting controls. These turn on all the artificial lights when sunlight is lost and lighting levels fall below the required lux level. To earn maximum savings, an automated lighting control system that turns on only enough artificial light to maintain the required lux levels is the best choice.

Skylights Provide Numerous Benefits to Commercial Buildings

Skylights have an overall effect of energy savings and reduced CO2 emissions. The bright, natural light let into an interior by skylights help create a pleasant environment, help inhabitants feel better and concentrate better, improve the building’s functionality and reduce energy consumption. All of these make skylights an ideal solution for commercial buildings.